#define _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>
struct ListNode {
    int val;
    struct ListNode* next;
    
};
struct ListNode* reverseList(struct ListNode* head)
{
    struct ListNode* n1 = NULL;
    struct ListNode* n2=head;
    if (head = NULL)
    {
        return head;
    }


    while (n2)
    {
        struct ListNode* n3 = n2->next;
        n2->next = n1;
        n1 = n2;
        n2 = n3;
        if (n3)
        {
            n3 = n3->next;
        }
    }
    return n1;



}
